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Title Phonons and Valence-band Splitting in Strained GaAs1-xNx/GaAs Epilayers
Authors (Tae Soo Jeong) ; (Hyeoncheol Kim) ; (Sukill Kang) ; (Kyu-Hwan Shim) ; (Taek Sung Kim)
Page pp.206-214
ISSN 1598-1657
Keywords Phonon; band splitting; strain; GaAsN
Abstract The strain effects in strained GaAs1-xNx epilayers are characterized by Raman spectroscopy and photocurrent spectra at various nitrogen composition. In addition, the nitrogen composition and the strain were determined by using high-resolution X-ray diffraction (HR-XRD). The Raman spectra are observed to be dominated by the GaAs-like longitudinal optical (LO) phonon mode as the strongest peaks show up around 289~294 cm-1. Moreover, the weak and broad peaks features in the range of 255~276 cm-1 originate from the peaks of GaAs-like transverse optical (TO) phonon mode and disorder induced, GaN-like LO. And the Raman peak shifts toward lower wave number with increasing nitrogen compositions, which is indicates the presence of tensile strain in the strained GaAs1-xNx epilayers. The valence-band splitting of GaAs1-xNx are obtained from photocurrent spectra. As the nitrogen concentration increases, the tensile strain in strained GaAs1-xNx epilayers increases while the valence-band splitting increases.